Pneumatic sheet feeding mechanism



June 26, 1962 A. FUX ETAL 3,041,067

PNEUMATIC SHEET FEEDING MECHANISM Filed Sept. 16, 1960 3 Sheets-Sheet 1 FIG.

INVENTORS. 2 AIME FUX y DONALD E. KAPLAN ATTO R NEY A. FUX ETAL PNEUMATIC SHEET FEEDING MECHANISM June 26, 1962 3 Sheets-Sheet 2 Filed Sept. 16, 1960 INVENTORS.

AIME BY DONA KAPLAN ATTORNEY June 26, 1962 A. FUX ETAL 3,041,067

PNEUMATIC SHEET FEEDING MECHANISM Filed Sept. 16, 1960 F/G. l0

INVENTORS.

AIME FUX 9e y DONALD E. KAPLAN ATTO RNEY 3,041,067 PNEUMATIC SHEET FEEDING MECHANISM Aime Fox and Donald E. Kaplan, Philadelphia, Pa, as-

signors to Burroughs Corporation, Detroit, Mich, a corporation of Michigan Filed Sept. 16, I960, Ser. No. 56,532 12 Claims. (Cl. 271-27) This invention relates generally to sheet feeding machines and more particularly to high speed feeding mechanisms for separating sheets one at a time in succession from a stack of sheets.

An object of the invention is to provide a feeder for successively feeding individual sheets from a stack of sheets.

Another object of the invention is to provide a sheet feeding mechanism wherein the endrnost sheet of a stack is maintained in operative feeding position and instantly released for feeding when a sheet is called for.

Still another object of the invention is to provide a fast acting sheet feeding mechanism which will commence separating succeeding sheets at the end of a stack before the previous sheet is completely separated from the stack.

A further object of the invention is to provide an instantaneously responsive control means for a sheet feeding mechanism which will restrain feeding of the endmost sheet of a stack of sheets disposed to the urging influence of a feeding member and release the sheet for feeding by the feeding member in the shortest possible time.

In accordance with the above objects and first considered briefly in its broad aspects, the invention utilizes a sheet gripping member, preferably in the form of a rotatable suction drum, for delivering sheets in succession from the end of a stack to sheet forwarding devices, and pneumatic means for controlling the effectiveness of the suction drum or sheet gripping member. For certain applications, the invention also contemplates the use of a separating member for moving a portion of the end sheet of a stack into operative feeding relation to the sheet gripping member. More specifically, the pneumatic control means takes the form of a control valve mechanism which is operable to restrain feeding of the end sheet of a stack. by the sheet gripping member or to release the sheet for feeding by said member.

The invention will be more clearly understood when the following detailed description of specific embodiments thereof is read in conjunction with the accompanying drawings in which:

FIG. 1 is a plan view of a sheet feeding mechanism constructed in accordance with the invention;

FIG. 2 is a sectional view taken along line 22 of FIG. 1;

FIG. 3 is an enlarged sectional view of a control valve mechanism taken along line 3-3 of FIG. 2;

FIG. 4 is similar to FIG. 3 but shows an operated condition of the control valve mechanism;

FIG. 5 is a sectional view of the control valve mechanism taken along line 55 of FIG. 4;

FIG. 6 is an enlarged view with parts broken away of a fragmentary portion of the mechanism shown in FIG. 1, illustrating a commutating shoe member in association with the rim of a suction drum;

FIG. 7 is an enlarged view of a fragment of the suction drum rim;

FIG. 8 is another view of the fragment shown in FIG. 7, taken in the direction of line 8-8 thereof;

FIG. '9 shows a modification of the sheet feeding mechanism of FIG. 1;

FIG. 10 is an enlarged sectional view taken along line 10--10 of FIG. 9, showing a forming shoe or separating member;

3,041,067 Patented June 26, 1962 FIG. 11 is a sectional view through the forming shoe taken along line 11--11 of FIG. 10; and

FIG. 12 is a view of a fragment of the forming shoe taken in the direction of line 12- 12 of FIG. 11.

Turning now to the drawings, and more particularly to FIG. 1 thereof, the preferred embodiment of the invention comprises a sheet stack receptacle or hopper 10 for supporting on edge a stack of sheets or cards 12. The cards 12 are advanced along the hopper table 14 toward the feeding mechanism 16 by means of a pusher 18 operated by any suitable drive device 'fragmentarily indicated by the numeral 19. In certain applications, as will appear more clearly hereinafter, the stack 12 may be advanced by gravity feed, if desired.

A suction delivery drum 20 is mounted for rotation on its central axis and is operable to be rotated from a suitable source of power, such as an electric motor, not shown, by means of a belt 21. The drum 20 is provided with a rim portion 22 formed with a plurality of minute ports or passages 24 (FIG. 2) which terminate at the outside periphery of the rim 22 in broad shallow grooves or orifices 26- (see also FIGS. 6, 7 and 8). In the present embodiment the passages 24 are positioned in the rim 22 in circular rows 28 (FIG. 2). The rows 28 are spaced apart in the present embodiment along the axis of the drum 20, to correspond with the spaces between the longitudinal rows of perforations in punched tabulating cards, to avoid loss of suction, as will become evident, if sheets or cards of that nature are being fed. The circular rows 28 of passages 24 are alternately staggered angularly about the drum 20 aids to avoid pulsations and provide a substantially smooth continuous suction force, as will be apparent more clearly hereinafter.

Adjacent to the drum 20 is a delivery chute 30 (FIG. 1) formed on one side by a guide member 32 and on the opposite side by a stripper bar 36 from which extend stripper fingers 34 a portion of which are freely disposed in circular grooves 35 in the rim 22.

A stationary commutating shoe 36 is in sliding contact with the inner surface of the rim 22 and is provided with a central opening or cavity 38 (\FIG. 6) in communication with a suitable source of vacuum, not shown, by means of a passage 4t and hose 42.

A control valve mechanism or valve 44 (FIG. 1) cornprises a stationary body 46 having a plurality of spaced apart shallow depressions or grooves 48 (FIG. 2) in the sheet or card engaging face 50 thereof. Each of a group of apertures or ports 52 communicates with a groove 48 and opens into an internal cavity 54 (FIGS. 3 and 4) which communicates with a source of vacuum, not shown, by means of a hose 55 (FIG. 2).

For controlling the flow of com-pressed air, as will appear more clearly hereinafter, the control valve mechanism 44 may be provided with any suitable valve which in the present embodiment prefer-ably takes the form of a sleeve valve 56 (FIG. 3) rotatably mounted in the body 46 and provided with a plurality of ports or passages 58 which lead into the central bore 60 thereof. The bore 60 communicates with a suitable source of compressed air, not shown, through a hose 68. The particular type of valve '56 was chosen for the present embodiment in order to provide a low-torque stepping valve which utilizes the leakage air around its periphery as an air bearing. A series of bleeder holes 62 (FIG. 5) communicate with circular recesses 63 in the outer surf-ace of the sleeve valve 56 for bleeding off the leakage air around the sleeve valve to prevent it from interfering with the suction applied to the cavity 54, as will be evident here inafter, when the valve 56 is in the condition shown in FIG. 3. The bleeder holes 62 communicate with a source of vacuum, not shown, through a passage 69 and hose 7@ for drawing or bleeding off the leakage air.

Arranged between the drum and control valve 44 (FIG. 1) is a fixed backing plate 72 having a face 74 substantially co-planar with the face 50 of the control valve 44 and substantially tangent to the drum 20.

In the operation of feeding sheets or cards from the stack 12, auxiliary air is supplied through a hose 75 (FIG. 1) from a suitable source, not shown, and directed to blow through an opening 77 in the hopper sidewall 78 against the ends of the endmost cards 12, thus to partially separate each endmost card from an adjacent card. The drum 20' is rotated continuously and suction applied continuously to the commutating shoe 36 to constantly maintain the cavity 38 at a reduced pressure. Suction is also applied continuously to the cavity 54 of the control valve 44 also to maintain it constantly at a reduced pressure. The sleeve valve 56 is initially in the condition shown in FIG. 3 and compressed air is supplied to it continuously through the hose 68 and bled off, as described above, through the hose 70. The magnitudes of the reduced pressure in the cavity 54 and the area that the grooves 48 occupy on the face 50 of the control valve 44 are so related respectively to the magnitudes of the reduced pressure in the cavity 38 and the area occupied by a group of orifices 26 on the periphery of the rim 22, which are at any time in communication with the cavity 38, such that the normal or card-holding force at the control valve 44 exceeds the normal or card-holding force at the drum 20 when the valve 56 is in the condition shown in FIG. 3.

The stack of cards 12 through the device 19 is urged by the pusher 18 against the control valve 44, the backing plate 72 and the drum 20. The leading portion of the end card of the stack is drawn against the rim 22 of the drum 20 by the suction being applied to the periphery thereof through the commutating shoe 36, the ports 24 and grooves or orifices 26. The drum 20 thus tends to feed the card from the stack but is restrained against so doing by reason of the higher card-holding or normal force being exerted on the trailing portion of the card through the suction applied through the cavity 54, ports 52 and grooves 48. To release the card for feeding by the drum 20, the sleeve valve 56 is rotated, or stepped, by any suitable device, not shown, from the condition shown in FIG. 3 to that shown in FIG. 4 at which time a linear row of passages 58 aligns with a group of ports 76. Each port 76 communicates with a groove 48 so that at this time a blast of compressed air is directed into these grooves across the face of the card. The compressed air in the grooves 48 diminishes the cardholding force of the suction applied through the cavity 54 so that when the pressure in the space between the card and the control valve 44 rises to a certain level the card-holding force being applied by suction to the leading portion of the card through the rim 22 of the drum 20 will then be effective for feeding and the drum will feed the card from the stack into the delivery chute 30. The card will be stripped from the drum by the fingers 34 and delivered to constantly rotating feed rollers 79 for forwarding to its destination.

A feature of the invention is the high speed with which the end card of the stack 12 responds to the suction applied to the drum 20 and the control valve 44. This is attained in the following way: First, the cavities 38 and 54 are constantly maintained at a reduced pressure. Second, the size of the ports 24 and 52 are extremely small in cross-section, or diameter, so that the reduced pressure in the respective cavities 38 and 54 does not change significantly from the condition where no card is present to that when a card is being retained by suction against the drum 20 and control valve 44. In other words, in order to draw a card to the drum 20 or control valve 44, it is only necessary to evacuate the orifices 26 or grooves 48 since the cavities 38 and 54 are already at a reduced pressure. And third, the orifices 26 and grooves 48 are cut or formed extremely shallow in the rim 22 and control valve 44 respectively to define an extremely small volume, and are of such broad shape as to define a maximum area for this small volume. Thus the normal force acting on a card 12 to hold it by suction against the drum 20 or control valve 44 is maximum, and the time required to reach this value, minimum. In this connection, the expression suction force as used in the claims is to be understood as the normal force obtained as the product of a difference in pressure between atmospheric pressure and a reduced pressure and the sheet or card-holding area with which such reduced pressure communicates.

FIG. 9 shows a modification of the embodiment shown in FIG. 1 in which the backing plate 72 is omitted and a stationary separating member or forming shoe 8%) placed in the same region. The trailing portion 82 (FIG. 11) of the face 84 of the forming shoe is co-planar with the face 50 of the control valve 44 while the leading portion 36 of the face 84 curves slightly away from the portion 82 to form a line substantially tangent to the drum 20. The plane of face 50 of valve 44 is spaced from the drum 2%). In the face 84 there is provided a plurality of spaced apart depressions or grooves 88 (FIG. 10) which communicate with passages 90 opening at their inner ends into a chamber 92 (FIG. 11) communicating with a suitable source of positive pressure, not shown, by means of a hose 94. Adjacent to the open ends 96 of the grooves 83 are the entrances 98 (see also FIG. 12) to passages 108 which communicate with a suitable source of suction, not shown, through a chamber 102 and a hose 104.

In the operation of the modification, the stack 12 is similarly urged by the pusher 18 against the control valve 44 and trailing portion 82 of the forming shoe 80 and air under positive pressure is directed into the hose 94 and flows across the surface of the end card 12 through the grooves 88 thus creating a low pressure area between the card and the forming shoe 80 which causes the leading portion of the card to separate more completely from the stack, after having been initially separated by air passing through the hose 75, and to move toward the leading portion 86 of the forming shoe face 84 until the leading end portion of the card is gripped suctionally by the drum 20. At this time and before the sleeve valve 56 is operated the card is being held, as described in the previous modification, by the control valve 44 and the drum 20. When the sleeve valve 56 is rotated to release the detained card for feeding by the drum 20, the flow of air through the grooves 88 and along the card provides also an air bearing for the card and operates also to commence moving the second or next card toward the drum 20 as the trailing portionof the end card leaves the vicinity of the forming shoe 80. The air flowing through the grooves 88 is drawn by suction around the tip 104 of the forming shoe 80 into the entrances 98 and passages so that it cannot operate to strip the card from the drum 20.

While there have been disclosed specific structures exemplary of the principles of the invention it is to be understood that these are but one form and modification thereof and that the invention may be constructed in a variety of sizes, shapes and modifications without departing from the true spirit and scope thereof. Accordingly, it is to be understood that the invention is not to be limited by the specific structures disclosed but only by the subjoined claims.

What is claimed is:

1. In a pneumatic sheet feeding mechanism, a feed member having a sheet engaging surface movable across the forward end of a sheet stack, means for applying a suction force to said surface to enable it to grip the forward portion of the end sheet of said stack for initially separating and feeding the sheet away from the stack, continuously operable pneumatic means for holding the rearward end of said end sheet to prevent feeding of said forward portion by said surface, and means operable to interfere with said pneumatic means while it is operating to render it ineffective to hold said sheet against feeding by said surface.

2. In a pneumatic sheet feeding mechanism, a rotatable feed drum positioned in substantial contact with the forward surface of the end sheet of a stack of sheets, said feed drum having internal passages each terminating in a shallow orifice in the periphery thereof, means for applying a suction force through said internal passages to said shallow orifices for feeding a sheet from the end of a stack of sheets, and means acting on the rearward surface of said end sheet for controlling the effectiveness of said suction force for enabling or preventing the feeding of said end sheet by said feed drum.

3. In a pneumatic sheet feeding mechanism, a feed member having a sheet engaging surface, means for applying a suction force to said surface for engaging the leading portion of the end sheet of a stack of sheets in the direction of feeding for feeding said sheet from the stack, a valve body having apertures therein and arranged to engage with a rearward portion of said sheet, means for applying a continuous suction force through said valve body apertures of greater magnitude than the suction force applied to said feed member surface to restrain feeding of said sheet and cause said rearward portion thereof to adhere to said valve body, and a pneumatic valve intermittently operable to direct a stream of air across said rearward portion of said sheet to render said continuous suction force ineffective to restrain feeding of said sheet by said feed member.

4. In a pneumatic sheet feeding mechanism, a feed wheel having a sheet engaging rim positioned for rotation across the forward surface of the end sheet of a stack of sheets, said rim having passages therein, means for applying a suction force through said passages to the periphery of said rim for feeding said end sheet from said stack of sheets, means for applying a stream of air in the direction of feeding toward said feed wheel and across the outer surface of said sheet to separate a leading portion thereof from the stack and cause it to move to said rim of said feed wheel to be suctionally gripped thereby, and selectively operable pneumatic means for pre venting feeding of said sheet by said feed wheel or releasing it for feeding while the sheet is under the influence or said suction force.

5. In a pneumatic sheet feeding mechanism, a feed member having a curve sheet engaging surface movable across the forward surface of the end sheet of a stack of sheets, means for applying a first suction force to said surface for suctionally gripping and feeding said end sheet away from said stack of sheets, and selectively operable pneumatic means for preventing feeding of said sheet or releasing said sheet for feeding while the sheet is under the influence of said first suction force and is gripped by said sheet-engaging surface, said pneumatic means including means for applying a second suction force continually on the rearward surface of said sheet of greater magnitude than said first suction force to effect said preventing function.

6. In a pneumatic sheet feeding mechanism, a rotatable feed drum positioned in substantial contact with the forward surface of the end sheet of a stack of sheets, said feed drum having passages each terminating in a broad shallow orifice in the periphery thereof, each said orifice occupying an area of said periphery greatly exceeding the cross-sectional area of each of said passages and being of such shallowness as to define an extremely small volume in said periphery, means for applying a suction force through said passages to said orifices for suctionally gripping and feeding said sheet from the end of said stack of sheets, and means operable on the rearward surface of said sheet for controlling the effectiveness of said suction force for enabling or preventing the feeding of said sheet by said feed drum.

7. In a pneumatic sheet feeding mechanism, a feed member having a sheet engaging surface, means for applying a suction force to said surface for engaging the leading portion of the end sheet of a stack of sheets in the direction of feeding for feeding said sheet from the stack, a valve body having ports therein and arranged to engage with a rearward portion of said sheet, means for applying a continuous suction force through said valve body ports of greater magnitude than the suction force applied to said feed member surface to restrain feeding of said sheet and cause said rearward portion thereof to adhere to said valve body, and a pneumatic valve operable to direct a stream of compressed air across said rearward portion of said sheet to interfere with said suction force through said valve body ports and to render it ineffective to restrain feeding of said sheet by said feed member.

8. In a pneumatic sheet feeding mechanism, a feed wheel having a sheet engaging rim, said rim having ports therethrough terminating in shallow grooves in the periphery thereof, means for applying a suction force through said ports to said shallow grooves for feeding the end sheet from a stack of sheets, means for applying a stream of air in the direction of feeding toward said feed wheel and across the outer surface of said sheet to separate a leading portion thereof from the stack and cause it to move to said rim of said feed wheel, means for exhausting said air to prevent it from stripping said sheet from said rim of said feed wheel, and selectively operable pneumatic means for restraining feeding of said sheet by said feed wheel or releasing it for feeding while the sheet is under the influence of said suction force.

9. In a pneumatic sheet feeding mechanism, a rotatable suction feed drum having a plurality of minute ports opening into the periphery thereof, said ports each terminating at said periphery in a broad shallow orifice therein defining a minute volume, each said orifice defining an area on said periphery greatly exceeding the cross-sectional area of each said port, a stationary commutating shoe in sliding contact with said feed drum and having a cavity therein in communication with successive groups of said ports when said feed drum is rotated, and means for applying suction to said cavity to maintain therein a predetermined reduced pressure and to draw a sheet from the end of a stack of sheets and cause it to seal a group of said orifices, and wherein the cross-sectional area of each said port is of such size as to cause a further reduction of said reduced pressure only to a negligible extent when said sheet seals said group of orifices.

10. In a pneumatic sheet feeding mechanism, the combination comprising, a feed member having a sheet engaging surface, means for applying a suction force to said surface for feeding a sheet from the end of a stack of sheets, a valve body having a sheet engaging surface formed with shallow depressions therein, said valve body having a first group of ports each communicating with a said depression and a second group of ports each opening at one end into a said depression and being normally closed at its opposite end, means for applying a suction force through said first group of ports of greater magnitude than the suction force applied to said feed member surface to restrain feeding of said sheet by said feed memher and cause it to adhere to said sheet engaging surface of said valve body and substantially seal said depressions, and a valve operable for opening said opposite ends of said second group of ports for applying therethrough a stream of compressed air into said depressions to render said suction force through said first group of ports ineffective to restrain feeding of said sheet by said feed member.

11. A combination as defined in claim 10* characterized further in that said valve body is provided with a cavity in communication with said first group of ports and said suction force applied through said first group of ports is such as to maintain a predetermined reduced pressure in said cavity, and wherein the cross-sectional area of each said port of said first group of ports is of such size as to '7 cause a further reduction of said reduced pressure only to a negligible extent when said sheet adheres to said sheet engaging surface of said valve body and substantially seals said depressions.

12. In a pneumatic sheet feeding mechanism, a delivery member operable to grip the end sheet of a stack of sheets and feed it away therefrom, a pneumatic shoe having a surface adjacent to said end sheet of said stack, said surface having a plurality of elongated depressions therein opening at least at one end adj aoent to said delivery member, means for applying a stream of air through said depressions and across said sheet toward said delivery member to separate a leading portion of said sheet from said stack and cause it to move toward said delivery member to be gripped thereby, means for applying suction to the region adjacent to said open ends of said depressions for exhausting said air to prevent it from stripping a said sheet gripped by said delivery member, a valve body having a sheet engaging surface formed with shallow grooves therein, said valve body having a first group of ports each communicating with a said groove and a second group of ports each opening at one end into a said groove and being normally closed at its opposite end, means for applying a suction force through said first group of ports of greater magnitude than the gripping force of said delivery member to restrain feeding thereby and cause said sheet to adhere to said sheet engaging surface of said valve body, and a valve operable for opening said opposite ends of said second group of ports for applying therethrough a stream of compressed air into said grooves to render said suction force through said first group of ports ineffective to restrain feeding of said sheet by said delivery member.

References Cited in the file of this patent UNITED STATES PATENTS Stevens Mar. 9, 1943 Mitchell July 14, 1953 Wendt et a1. Jan. 7, 1958 

